Enduro21 gives the long term test GASGAS EC300 GP a front end upgrade with the WP 6500 cartridge kit – drop-in suspension parts that have transformed our bike.

We’re kicking ourselves here at Enduro21. Four months down the line of having the GASGAS EC300 GP test bike in our hands and only now did we think to check if the WP 6500 fork cartridge kit would fit.

Our time testing the 300 GP has been pretty sweet, and we still haven’t gotten over how good the bike looks (and how many comments we get wherever we ride). But one factor you cannot escape is the standard open cartridge forks and their limitations for racing.

We understand why GASGAS opt for the open cartridge spec forks in their enduro model range – they say expectations of customers is in a different place to other more race-focused bikes and the spec is also reflected in the retail price.

But this GP edition sells itself on being a race replica and for our money that means it has a different perspective to other EC (enduro) GASGAS models. It looks like a race bike, it promises to be a race bike, then it should be able to race and though we have been doing exactly that these last months, the fork performance in a race situation has been feature.

Why the standard forks need upgrading

A recent timecard enduro in a forest left us with some great hand blisters from hanging on as those forks tried to bounce and buck us off the beaten track for the tight time checks.

To sum the open cartridge forks up; once you start to push beyond their level, they lack compression and damping control, don’t absorb and bounce back off bumps and make the handling both hard work and not as stable as it should be.

GASGAS say one of the reasons they choose the open cartridge forks is because they cause the oil to foam and that makes the ride more comfortable. In a race situation we say this doesn’t work and for a bike so clearly designed to tell the world about GASGAS race heritage, it is confusing why they chose this specification fork.

Doh! moment

Fast forward a week or two from that forest time card enduro and we’re in the workshop when the WP box on the shelf catches our eye. A few minutes of thinking, followed by some “will these fit?” messages to GASGAS and WP – who were quick to get back to us:– and the answer was yes, it’s the same part number. They will fit.

*To be clear, there are different 6500 kits available for a range of bikes and in different specification depending on riding situations. For example enduro or motocross, KTM/Husqvarna/GASGAS or Beta for example.

Cue a lot of cursing and questioning why we didn’t think of this before…

WP 6500 fork cartridge kit technical highlights:

• Improved feedback from the track in different riding situations
• Closed cartridge units
• Pressurised system reduces cavitation risk for no damping loss
• Extreme longevity due to the use of only high-quality materials
• Wide range of adjustment with all settings adjusted externally
• Spring preload fully variable
• Handcrafted parts

Fitting the WP 6500 fork kit

If you’re half savvy with the spanners and have the correct tools to fit suspension parts – in this case mainly the 50mm fork top spanner and the C-spanner, or stopper, to hold the rod to tighten the damping adjustor – then this shouldn’t be a hard workshop task.

A 17mm spanner and a fresh bottle of oil, containers for the old oil and ideally a bench vice should let you get this job done pretty quickly.

Shown above are the two cartridges, 6500 nearest and standard part the other side of the spring.

This isn’t a fitting guide however, but a test of the WP 6500 fork kit, so we’ll steer away from guiding you through the process and instead focus on how the parts work on this bike.

Enduro tests – bike transformed

To add to the positive vibes we aimed at with this upgrade to the front end of the GASGAS, we also bolted on another off-the-shelf part, the Brembo front brake caliper.

Both the WP fork kit and the Brembo caliper are parts which are in good condition but, just to quash any cynical Enduro21 readers who think we get all this stuff for free, we bought both probably five or so years ago to use on our own bikes.

Both the fork kit and the caliper are available from a GASGAS/WP dealer as upgrades.

One giant leap

Maybe giant leap is too strong but if you ride a standard enduro bike and wonder why you’re struggling to stay on a line, find riding hard work in rough conditions and you get blisters, then quite likely your suspension needs looking at and this kit could well be the answer.

Designed as a more budget-friendly solution compared to the full WP Cone Valve forks. Though a decent amount less dollar than the Cone Valves, they are not a million miles away in terms of performance for regular riders like us.

Put simply they replace the internals of the stock forks, use just the springs and the complete outers to give you a fork upgrade in performance and adjustability.

Feel good factor

The first thing you notice is the forks don’t drop so readily under the bike’s own weight or when you get on it. They hold up better, literally, and that starts the positive feeling they give off. After the soft, open cartridge stock forks, our EC300 GP sits a fraction taller with the kit installed – or rather it sags less when you get on the bike.

On the track or trail the difference is immediately clear as the front of the bike has more control under braking and hitting bumps – you feel like the suspension stroke more and rather than it being something you rush through in and out of corners or hitting bumps it is more supportive.

Having less active front end and more control makes the Gasser more accurate and precise too, which obviously is a good thing. Bump absorption is more controlled which means the front tyre has an easier life and all the above combined means the bike is easier to ride.

Traditional adjustability

To all intents and purposes fitting the WP 6500 cartridge kit makes the forks look like they are Cone Valves. The red top caps, the compression and preload adjustment and red rebound bottom caps all look similar.

Compression and rebound adjusts through clickers on the top and bottom of the fork legs with a more traditional one in each fork leg. The range of adjustment is wide and meaningful with one or two clicks making a difference to the feel and handling – we’ve used this same kit with a softer setting in hard enduro and harder on an MX track.

The 6500 kit comes with a flat fork top “screwdriver” to make compression adjustments easily at the track.

Preload is adjustable with the ring-spanner provided plus you can use the stack of plastic spacers which come in the box. We have never used the preload spacers because, for enduro and at the speed we ride, the standard setting is good.

If you’re faster or spending more time on the moto track (the 6500 kit is available for different bikes including MX models and not just from the Austrian manufacturer) you have the option to increase the stack behind the spring.

Note we also used the standard springs from the OEM forks with the 6500 units, which is recommended if you are within the “average rider” weight range.

How does it work with the standard WP shock?

With the 6500 kit up and the stock WP Xact rear shock you might expect a mismatch in handling. If anything, the opposite is true as the rea of the bike started to behave itself a bit better.

The shock gets an easier time because the whole bike is behaving better and overall we’d say the shock works well enough to match the fork upgrade.

That said, the new design shock absorbers on the latest generation Austrian bikes have limitations and in our experience don’t control the rebound “kick-back” well enough.

*One option would be to try the WP bladder kit for the shock on this bike and it would help control that kick better. In terms of being cost effective alongside the fork kit it makes sense also.

But our test at this beaten-up sprint enduro showed the shock was capable enough and with the fork kit contributed to a much better handling bike. 

Enduro21 Verdict

So, the handling of the GASGAS EC300 GP is improved, steering is more precise and you can push harder to ride faster – that’s what this bike should have been capable of all along, right?

Honestly speaking it was a bit of a revelation and proof this kit is worth its weight having fitted it now to different Austrian bikes from our 2019 TPI Husqvarna 250 to this 2025 GASGAS EC300 GP.

If you’re a fan of buying a piece of kit which you can transfer across different bikes as you change or upgrade the 6500 cartridge kit fits that bill. The same goes for fans of a quick and easy way of sorting out problem area of a standard bike.

Yers, the 6500 is an added expense on top of a bike but given the fact we ahev fitted it and used it in so many different bikes now over a period of years, it has certainly earned its place.

More information and your nearest WP dealer: www.wp-suspension.com

Photo Credit: Enduro21 + Michael Bennett (main image)